1. Field of the Invention
The present invention relates to an optical disk drive, a disk cartridge and an optical storage system provided with them. Moreover, the present invention relates to a media convertible storage system used to record, reproduce and keep a high density information, and more particularly relates to an optical storage system including an optical library.
2. Description of the Related Art
Conventionally, as a large capacity memory unit employed in a video camera, a computer and the like, a media convertible memory unit is mainly used, such as a magnetic tape, a fixed magnetic disk, an optical disk or the like. In the magnetic tape memory unit, the magnetic tape accommodated in a tape cartridge is inserted in a tape drive, and a data is sequentially recorded in conjunction with winding of a tape. Making the tape longer increases a record area to thereby increase its storage capacity. The fixed magnetic disk tries to cancel out the influence of dust and the like, by designing the closed structure that a magnetic disk is built in the disk drive. Further, the fixed magnetic disk tries to increase its storage capacity by making a magnetic head extremely close to the surface of the disk. The disk is fixed to a spindle motor to thereby reduce a chucking error and a run-out of the disk, and accordingly insure a rapid access and a stable operation. Also, in the media convertible storage system, a disk cartridge using a magneto-optic effect and a phase change is standardized by ISO and the like. In this disk cartridge, since a record area of the media is limited, it is inferior in storage capacity to the magnetic tape. However, access can be arbitrarily done to recorded information. Thus, it is possible to quickly correspond to a reproduction of desirable information.
The disk cartridge has the following structure. That is, when it is inserted into the optical disk drive, a shutter is opened to accordingly expose the optical disk, which enables the access to the optical head or the chucking of the spindle motor. The disk cartridge is slower in access speed than the fixed magnetic disk because of a chucking error to the spindle motor when the disk cartridge is accommodated in the optical disk drive and a weight of the optical head. On the contrary, the disk cartridge is superior in storage density. Moreover, it is used to keep the large-scale information by taking advantage of the media convertible type.
In recent years, a processing amount of information has been increased due to the large improvement of performance of CPU, peripheral parts and the like in a computer and the great progress and complexity of a software. Moreover, a TV broadcast and a video camera are largely digitized so that image information is captured and treated in the computer. Under such situation, the access to the recorded information cannot be done arbitrarily, in the memory using the magnetic tape. Thus, it is not suitable for a process, such as information edition or the like. Also, it is difficult in management to store all information in one fixed magnetic disk. Hence, it is impossible to cope with the increase of the accumulating information amount. Moreover, if crush of a floating magnetic head and the like occur, the whole memory cannot be used, which results in the loss of all the recorded information.
The media convertible storage system employing the disk cartridge is superior in random access to recorded information. Also, it is superior in correspondence to management of high-density information and an increasing information amount. However, the structure, in which the surface of the optical disk is exposed, causes dust, oil mist, vapor, bacteria and other minute particles in ambient air to be sucked into interior of the apparatus and further invade in the gap between the optical head and the surface of the optical disk and finally damage the recording and reproducing functions. Even in the optical disk, it is necessary to make the optical head extremely close to the surface of the optical disk in order to increase the storage capacity. Hence, any minute foreign material should be avoided from invading.
If the combination usage of the fixed magnetic disk system and the media convertible storage system tries to solve the above-mentioned problems, this results in new problems of increase of an apparatus installation space and a high cost.
Moreover, in the conventional optical library, a space in which a mechanism for mounting and detaching the optical disks or the disk cartridges in or from the optical disk library is complex, and a wide space is necessary, which causes the optical library to be made larger, and the cost to be expensive, and the reliability to be deteriorated.
Furthermore, the conventional disk cartridge requires a mechanism for opening and closing a shutter of the disk cartridge and then chucking the optical disk on the spindle motor, which results in the problems of the larger scales of optical disk drive, the higher cost, the deteriorations of reliability and the like.